Preparation

Fill medium bowl with cold water. Squeeze juice from lemon into bowl; add lemon. Cut off stem and top quarter from each artichoke. Bend back dark green outer leaves and snap off at artichoke base until only pale green and yellow leaves remain. Quarter each artichoke. Using small spoon, scoop out choke and any purple-tipped leaves. Transfer to lemon water.

Heat oil in heavy large skillet over medium heat. Add onion; sauté until soft, about 5 minutes. Drain artichokes; add to skillet along with carrots. Cover; cook until vegetables are crisp-tender, stirring often, about 8 minutes. Add asparagus and sugar snap peas. Cover; cook until vegetables are tender, stirring and adding water by tablespoonfuls if vegetables begin to brown, about 8 minutes. Stir in chervil. Season with salt and pepper.